In these days, there is high requirement of producing a packaging bag provided with an easily opening mechanism and a mechanism for freely opening and closing an opening of the opened packaging bag. Specifically, it is required to provide a fastener bag having both functions in a technical field of an automatic filling and packaging bag capable of simultaneously filling a content in the bag and packing the bag.
The applicant of the subject application has provided, in order to satisfy the above requirement, an invention relating to a flat-bag-type fastener bag which is formed with a cut-open portion along an extending direction of a fastener of this fastener bag so as to tear the flat bag in this direction to thereby open the same (Japanese Patent Application No. 2000-302725).
However, in the case of this flat-bag-type fastener bag, a portion from which a content filling hopper is inserted into a bag body is not widened so much, and this matter constitutes an obstacle for improvement of working efficiency. In addition, there may cause a case such that a cutting-starting portion of the cut-open portion, from which the bag is torn and opened, is not well formed.
On the other hand, it has also highly been required to provide a packaging bag having an opening suitably in accordance with kinds of contents to be filled up.
Then, an object of the present invention is to provide a fastener bag surely formed with a cutting-starting portion with an improved working efficiency.